The latest global market-share estimates for smartphones are out. And as we've come to expect from these regular exercises in mobile OS number-crunching, the news is bright for Apple and Google, but a bit bleak for Nokia, Research In Motion (RIM), and Microsoft.

Research firm Canalys released its final smart phone market estimates for the second quarter of 2011, which show that Google's Android mobile operating system now has nearly half of the worldwide smartphone market--48 percent, to be exact. Of the 56 countries Canalys tracks, Android leads in 35 of them.

Nearly 52 million Android-based smartphones shipped in Q2, a staggering 379-percent increase over a year ago. Android has been the top platform by shipments since the fourth quarter of 2010, according to Canalys.

Apple's iOS platform had a stellar second quarter as well. Apple shipped 20.3 million iPhones in the second quarter and grabbed 19 percent of the global market, as iOS passed Nokia’s Symbian platform to take second place.

Perhaps more impressive is the fact that Apple is now the world’s leading individual smart phone vendor, passing longtime leader Nokia.

"With the next-generation iPhone anticipated in Q3, it’s likely that Apple’s position will grow even stronger in the second half of the year,’ said Canalys analyst Chris Jones in a statement.

Nokia in Transition

While Nokia continues to do well in emerging markets, including Brazil, Russia, India, and China, demand for its Symbian-based smartphones is fading fast, particularly in Western Europe, where the manufacturer has been strong in the past, says Canalys analyst Pete Cunningham, who believes Nokia "badly needs" its Windows Phone handsets to launch soon to regain market share.

While Nokia plans to launch a Windows Phone before the end of the year, it will be some time before the Finnish company offers a range of Windows handsets to (hopefully) boost sales volumes.

Microsoft waits for Nokia's first Windows phones, and it also sees its global market share slipping too. Canalys reports that fewer than 1.5 million Microsoft-based smart phones shipped during the second quarter, giving Redmond just 1 percent of the global market--down 52 percent from a year ago.

RIM, meanwhile, fared poorly in North America, where its market share fell to 12 percent, down from 33 percent from a year ago. However, the BlackBerry-maker's global shipments grew 11 percent, and it remained the top vendor in Latin America with a 28-percent share.

To stay competitive globally, RIM needs its upcoming BlackBerry OS 7 to be a hit. But perhaps things aren't as bleak as they seem.

"It’s easy to be negative about BlackBerry in the U.S., but it’s important to remember that in other markets, particularly emerging markets, it continues to see significant interest and uptake of its devices, for example in Indonesia and South Africa where it is the leading smart phone vendor," said Jones.